1. Field of the Invention
The present invention relates to a feeder device for a receiving apparatus and, more particularly, to a feeder device and associated method for feeding a media unit, the feeder device being capable of feeding multiple thicknesses of media units and having an increased media capacity.
2. Description of Related Art
A printer device such as, for example, a printer as described herein typically includes a feeder for supplying media, such as individual cards, to the printer, a print engine which includes a transport mechanism for transporting the card through the printer and a printing mechanism for printing on the individual cards, and an exit or output hopper for receiving the printed cards. Further, the feeder generally comprises a card hopper for receiving the stack of cards to be fed, in addition to a drive mechanism for feeding the cards to the print engine. A gate at the exit of the feeder, otherwise known as the outlet opening, can include a separation mechanism for separating individual cards, usually an end card, from the stack in order to feed only one card to the print engine at each feed cycle.
Such a card feeder may be used on other card processing systems, such as a patch lamination system, a magnetic card or smart card encoding system, or the like. The drive system generates the driving force for the end card and the separation mechanism generates a separation force on the stack so as to allow the end card to be separated therefrom. With such a card feeder system, a general intent is to provide a driving force on the end card that is greater than the separation force imparted on the stack under many conditions that can exist in the card feeder. The separation force exerted by the separation mechanism on the stack typically has to be greater than a sticking force that can exist between the end card and the remainder of the cards in the stack. This sticking force may be related to, for example, electrostatic discharge (“ESD”) between cards, cut or folded card edges, the weight of the stack on the end card, the thickness of the cards in the stack, or other factors or combinations thereof.
In order to address these concerns in a card feeder, a compromise often must be achieved between the separator mechanism, which exerts the separating force on the stack that must be greater than the sticking force between the stack and the end card, and the drive system, which must provide a driving force greater than the separating force, regardless of the type, thickness, condition, and quantity of the cards in the stack. To this end, some previous feeders included, for example, a drive roller acting on the leading edge of the end card for drawing the end card from the card hopper, wherein the card hopper was configured to receive the cards in a uniformly stacked manner, similar to the in-package condition, prior to the cards being fed by the feeder mechanism. However, the drive roller/uniform stack hopper configuration was often unreliable for providing a driving force greater than the sticking force between cards in the stack. Such previous feeders also included, for example, a rigid gate for facilitating separation of the end card from the stack, with the gate being adjustable, in some instances, to correspond to the thickness of the card to be fed. For various reasons, such as ineffectiveness with warped cards or varying thickness among cards, such a rigid gate was a generally unreliable solution. In other instances, such previous feeders included a mechanism associated with the card hopper for adding weight on the cards in the stack, including the end card, for increasing the driving force (or maintaining the driving force at an acceptable level) on the end card when only a few cards remained in the hopper. Such a mechanism, however, often hampered efforts to add more cards to the stack during the printing process.
Some modifications to such previous feeders were also attempted in order to obtain desirable feed conditions for cards in the stack. For example, some feeders included an additional drive roller configured to act on the trailing edge of the card, or varied the shape and/or material comprising the roller(s), in order to increase the driving force on the end card, with respect to the adhesive or sticking force between the end card and the remaining cards in the stack upon initiation of the feeding process. In other instances, the stack of cards was oriented at an angle with respect to the drive mechanism so as to laterally shift adjacent cards to as to reduce the adhesive or sticking force therebetween. In still other instances, the outlet opening included a gate device configured to allow the operative height of the outlet opening to be adjusted according to the thickness of the end card so as to increase the separation force on the remaining cards in the stack. Other modifications implemented a mechanism for maintaining a constant force or weight on the stack of cards regardless of the amount of cards remaining in the hopper. However, such devices remained limited in effectiveness and reliability in instances of card thickness variation within a stack or warped card, or otherwise limited access to the cards remaining in the stack during the feeding process.
Thus, there exists a need for a feeder device capable of supplying media, such as cards, stock, paper, cardboard, etc. to a processing system, such as a print engine, in a secure, reliable, and efficient manner, without such undesirable occurrences as, for example, multi-card feeding or misfeeds, if the hopper is not empty. Such a feeder device should desirably provide effective media feeding for different types of material, for different thicknesses, and for media throughout the stack of media, from the first media unit to last media unit in the stack.